Holocene hydroclimate, fire, and the persistence of coniferous sub-alpine rainforest in Tasmania, Australia

Climate change is amplifying pressures on ecosystems, highlighting the need to provide baseline data on how ecosystems have responded to warm intervals over the long term, particularly with respect to extreme events such as wildfire and drought. This study investigates the impacts of Holocene climate and fire on the threatened, fire-sensitive conifer, Athrotaxis cupressoides , a species endemic to Tasmania, Australia. We combine palaeoecological data from Lake McCoy with a speleothem hydroclimate record from nearby Kubla Khan Cave to reconstruct regional vegetation-fire-climate dynamics over the last 6100 years. Results reveal a strong relationship between local hydroclimate, fire frequency and A. cupressoides persistence, with the species declining at times of high fire frequency and increasing during phases of higher regional water balance. Athrotaxis demonstrated remarkable resilience to fire throughout the mid-to-late Holocene, particularly during periods of higher moisture. A shift to a persistently wet climate in northern Tasmania since 2.1 ka stands in contrast with regional trends experienced across western Tasmania. Increased moisture depressed fire in the catchment, facilitating the development of A. cupressoides rainforest atop Sphagnum wetlands. Our results highlight that ecosystem resilience to fire is modulated by local hydrology, a finding that can feed into conservation strategies aimed at protecting Athrotaxis in Tasmania. The resistance of the host rainforest against invasion of neighbouring sclerophyll communities at times of high fire frequency underscores the significance of local hydrology in maintaining ecological stability. This research contributes to a nuanced understanding of climate-vegetation dynamics in topographically complex regions and reinforces the importance of localised multi-archive climate records in palaeoecological studies.